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Colacodasya australica Womersley, sp. nov.

Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae

Thallus light red-brown, pulvinate to globose, 2–4 mm across, with a central pseudoparenchymatous tissue and short, peripheral, free polysiphonous branches (Fig. 235C). Attachment by rhizoids (Fig. 235A) penetrating between host cells; epiphytic on axes of Dasya clavigera. Structure. Central tissue of irregularly branched filaments linked laterally by secondary pit-connections, cells elongate to ovoid, inner cells 40–90 µm in diameter, outer cells 25–40 µm in diameter; attachment rhizoids penetrating between host cells, 15–25 µm in diameter with cells L/D 2–4, cells later becoming irregular and 30–60 µm across. Peripheral free filaments (Fig. 235C) becoming polysiphonous (Fig. 235G) with 5 pericentral cells, 70–170 µm in diameter with segments L/D 0.8–1.5, ecorticate but with ovoid cells 12–25 µm in diameter cut off from both ends (Fig. 235B) of the pericentral cells. Apices probably sympodial, with pseudolaterals borne radially from each segment and branched from each (occasionally second) cell, upper filaments unbranched and 5–10 cells long. Pseudolaterals with lower cells 20–45 (–60) µm in diameter and L/D 1–2.5 (–4), tapering to apical cells (often lost) 12–22 µm in diameter, subapical cells L/D (1–) 2–4, apical cell short. Rhodoplasts discoid, pale in colour.

Reproduction: Gametophytes monoecious. Procarps borne on basal cells of pseudolaterals which cut off 5 pericentral cells, with a 4-celled carpogonial branch and associated sterile cells. Cystocarps (Fig. 235D, E) ovoid, broad based, 200–450 µm in diameter with a slight broad neck and borne laterally on a polysiphonous branch; gonimoblast much branched, with basal cells scarcely fusing, carposporangia in short terminal chains, ovoid, 7–15 µm in diameter. Pericarp with 12–14 erect filaments, 3 cells thick with ovoid, irregularly shaped and placed outer cortical cells 12–25 µm in diameter. Spermatangial branches (Fig. 235F) on the same thallus as cystocarps, developed as single or paired terminal branches of pseudolaterals, 75–150 µm long and 25–35 µm in diameter, with or without a terminal row of sterile cells.

Tetrasporangial stichidia (Fig. 235G) lanceoid to cylindrical, 100–400 µm long and 50–70 µm in diameter, borne as branches of pseudolaterals on a monosiphonous base, with 5 pericentral cells and tetrasporangia per whorl, tetrasporangia 15–25 µm in diameter, each with 2 (undivided) ovoid cover cells which remain more or less erect and cover the lower half of the sporangia.

Type from Port Elliot, S. Aust., on Dasya clavigera (on Amphibolis antarctica), upper sublittoral (Parsons, 1.xii.1967; AD, A31895 -"Marine Algae of southern Australia" No. 401).

Selected specimens: (all on Dasya clavigera): Hopetoun, w. Aust., drift (Parsons, 20.xi.1968; AD, A33354). Nanarup, 30 km E of Albany, W. Aust., upper sublittoral (Parsons, 18.xi.1968; AD, A33370). Elliston, S. Aust., on outer reef (Parsons, 16.v.1968; AD, A32566). Stinky Bay, Nora Creina, S. Aust., upper sublittoral on reef surface (Womersley, 6.xii.1995; AD, A64759). Robe, S. Aust., reef surface, west coast (Goff & Womersley, 13.ix.1983; AD, A54288 -"Marine Algae of southern Australia" No. 401a). Vivonne Bay, Kangaroo I., S. Aust., 3–4 m deep on jetty piles (Latz, 22.xi.1968; AD, A33023). Pennington Bay, Kangaroo I., S. Aust., in shallow reef pools (Parsons, 17.xi.1967; AD, A32066). Port MacDonnell, S. Aust., upper sublittoral on reef edge (Parsons, 11.ii.1968; AD, A32582).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Hopetoun, W. Aust., to Port MacDonnell, S. Australia.

Taxonomic notes: C. australica is often common on Dasya clavigera and is to be expected anywhere the host occurs.

The other 2 species of Colacodasya, while similar in habit, show clear differences from C. australica. The type species, C. inconspicua (Reinsch) Schmitz occurs on Heterosiphonia merenia, is distichously branched and has 6 tetrasporangia per segment, with undivided cover cells; Levring (1945, p. 25) considered it closest to Heterosiphonia. The other species, C. californica Hollenberg (1970, p. 65), occurs on Heterosiphonia erecta, branching is uncertain, and there are 4 tetrasporangia per whorl with divided and transversely elongate cover cells.


HOLLENBERG, G.J. (1970). Phycological notes IV, including new marine algae and new records for California. Phycologia 9, 61–72.

LEVRING, T. (1945). Marine algae from some antarctic and subantarctic Islands. Lunds Univ. Årsskr. N.F. Avd. 2, 41 (7), 1–36, Plate 1.

The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.

Author: M.J. Parsons and H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustration in Womersley Part IIIA, 1998: FIGS 235.

Figure 235 image

Figure 235   enlarge

Fig. 235. Colacodasya australica (AD, A31895). A. Rhizoids of Colacodasya (above) penetrating the host. B. Erect branch showing pericentral cells and small nodal corticating cells. C. Outer part of pulvinate base with young erect branches. D. Cystocarps on erect branches. E. A cystocarp with ovoid carposporangia. F. Spermatangial branches on erect surface branches. G. An erect branch with stichidia.

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